The present invention relates to a safety apparatus and protection method for machines having a moving member.
The invention has particular, although not exclusive, utility with respect to press brakes and other types of machines having a working member that operates against a work-piece supported by a supporting member, whereby one of the members is controlled to selectively move convergingly towards the other member of the machine. With these types of machines an operator generally works in close proximity to, and can have a body member enter, the neighbourhood of the working member during traversing of the moving member. This moving member may comprise the working member, such as in a normal down-stroking press brake or it may comprise the work-piece supporting member such as occurs in an up-stroking press brake.
The invention is a development of the safety apparatus disclosed in Australian Patent Application No. 27084/92, which is incorporated herein by reference. It is an object of the present invention to protect objects entering the neighbourhood of a working member of a machine that operates against a workpiece supported by a supporting member, whereby one of the members is controlled to selectively move convergingly towards the other member of the machine.
Moreover, it is a preferred object of the invention to prevent the object from being impinged by that member of the machine which moves.
In accordance with one aspect of the present invention, there is provided a safety apparatus for a machine having a working member provided with a working end and a work-piece supporting member, whereby one of the members is controlled to selectively move convergingly towards the other member of the machine, the safety apparatus including:
corresponding light emitting means and light receiving means for mounting in fixed relationship with the working end of a working member, so as to define a protected region fixedly spaced therefrom;
said light emitting means being adapted for emitting a beam of light and the corresponding light receiving means being adapted for receiving the beam of light so that normally the beam may be emitted and received by said corresponding light emitting means and light receiving means along an uninterrupted path fixedly spaced from the working end of the working member;
control means to activate said light emitting means to emit the light beam and said light receiving means to sense receipt of the emitted light beam during a range of prescribed movement of the moving member, said range of prescribed movement being completed at a mute point and the moving member being capable of continuing to move through a further range of prescribed movement past said mute point;
halting means for halting advancing movement of the moving member in response to some contingency as detected or sensed by said control means.
Preferably, said control means includes moving member control means to control the direction or speed of movement of the moving member of the machine.
Preferably, said moving member control means includes:
input signals from one or more of:
said halting means,
said machine operator or operators, via hand control, switches, or other input device, or
machine sensors, such as pressure and limit switches;
moving member control processing means; and
output control signals, to control valves, relays, or other control devices.
Preferably, said halting means is disabled from halting advancing movement of the moving member for certain contingencies during said further range of prescribed movement.
Preferably, said control means includes position processing means to continuously track the movement of the moving member and check that said movement is in accordance with said prescribed movement; and wherein said halting means halts advancing movement of the moving member in response to said position processing means determining that said advancing movement is not in accordance with said prescribed movement.
Preferably, said position processing means includes tracking means to measure instantaneous movement of said moving member, said position processing means recording said mute point relative to the position of said moving member as measured by said tracking means and thereafter continuously checking for the occurrence of the measured location of the mute point as determined by said tracking means for effecting control of the movement of said moving member.
Preferably, said control means includes pulsing means to cause said light emitting means to generate the light beam so that it is pulsed in a prescribed manner, and light control and processing means to control the operation of said pulsing means and process signals received by said light receiving means to determine when the emitted light beam is not received or pulsed in said prescribed manner; and wherein said halting means halts advancing movement of the moving member in response to said light control and processing means determining that the emitted light beam is not received or pulsed in said prescribed manner during said range of prescribed movement.
Preferably, the safety apparatus includes a plurality of corresponding light emitting means and light receiving means to be disposed to define a barrier of light paths around the leading edge, and said pulsing means being adapted to cause each of said corresponding light emitting means and light receiving means to be pulsed in a different manner to differentiate between them.
Preferably, said control means includes vibration sensing means to analyse signals in response to said light receiving means sensing receipt of the light beam and distinguish between normal vibration of the light beam and abnormal interruption of the light beam; and wherein said halting means halts advancing movement of the moving member in response to said vibration sensing means sensing said abnormal interruption of the light beam during said range of prescribed movement.
Preferably, said light emitting means is mounted at one end of the active member and said light receiving means is mounted at the opposing end of the active member so that vibrational movement of the corresponding light emitting means and light receiving means which causes oscillatory movement of the emitted light beam is damped in one dimension transverse to the path of said light beam to essentially confine the resultant oscillatory movement of the light beam to a single transverse dimension substantially orthogonal to said one dimension to reduce the detection time taken in sensing a said abnormal interruption of the light beam.
Preferably, a plurality of said corresponding light emitting means and light receiving means are provided so that said light emitting means are integrally mounted in substantially parallel relationship adjacent to each other as a discrete unit relative to the active member and said light receiving means are integrally mounted in substantially similar parallel relationship adjacent to each other as a separate discrete unit relative to both the active member and said discrete unit, but in substantial alignment with said corresponding light emitting means to receive the respective emitted light beams therefrom, such that vibrational movement is imparted to each discrete unit as a whole causing synchronous and corresponding oscillation to said light beams and synchronous and corresponding sensing of uninterrupted passage of said light beams by said light receiving means, thereby facilitating the analysis and discrimination of the received light beams by said vibration sensing means.
Preferably, said moving member tracking means continuously checks the distance advanced by the moving member beyond said mute point with a prescribed maximum distance and if receipt of the emitted light beam is not interrupted within said prescribed maximum distance signals said halting means to halt further advancing movement of the moving member.
Preferably, said safety apparatus includes operator interface means to accept instructions from the operator, and to display information back to the operator; whereby said operator interface is constructed to identify certain specific conditions, and other information being coded to identify different faults and operation conditions.
Preferably, said control means includes step-up means to disable said halting means and selectively determine the limits of said prescribed movement and position of said mute point via said tracking means.
In accordance with another aspect of the present invention, there is provided a method for protecting an object entering into the path of a moving member of a machine, the moving member being either having a working member provided with a working end, or a work-piece supporting member, whereby one of the members is controlled to selectively move convergingly towards the other member of the machine, the method including: emitting a light beam at a fixedly spaced distance along a normally uninterrupted path in advance of the working end of the working member whilst the moving member moves through a range of prescribed movement, said range of prescribed movement being completed at a mute point and the moving member being capable of continuing to move through a further range of prescribed movement past said mute point;
continuously sensing for the receipt of said light beam after it has traversed in advance of the working end; and
halting the advancing movement of the moving member in response to any failure to receive and sense the emitted light beam at any time during said range of prescribed movement or in response to some contingency.
Preferably, the method includes preventing the moving member from being halted for certain contingencies during said further range of prescribed movement.
Preferably, the method also includes continuously tracking the movement of the moving member, checking that said movement is in accordance with said prescribed movement ,and halting advancing movement of the moving member whenever the movement is not in accordance with said prescribed movement.
Preferably, the method includes pulsing said light beam in a prescribed manner and halting the advancing movement of the moving member in response to failing to receive and sense the emitted light beam as pulsed in said prescribed member at the other end of the active member.
Preferably, the method includes emitting and sensing the receipt of a plurality of light beams disposed to define a barrier of light paths around the working end of the working member, each light beam being pulsed in a different manner to differentiate between them.
Preferably, the method includes analysing the received light beam to discriminate between normal vibration and abnormal interruption of the light beam and halting advancing movement of the moving member in response to sensing said abnormal interruption during said range of prescribed movement.
Preferably, the method includes damping vibrational movement of the light beam in one dimension transverse to the path of said light beam to essentially confine resultant oscillatory movement of said light beam to a single transverse dimension substantially orthogonal to said one dimension to reduce the detection time taken in sensing a said abnormal interruption of the light beam.
Preferably, the method includes emitting a plurality of light beams in substantially parallel relationship to each other such that vibrational movement from the machine is imparted equally to said light beams causing synchronous and corresponding oscillation of said light beams facilitating the analysis and discrimination of same.
Preferably, the method includes completing said range of prescribed movement at a mute point and continuing movement of the moving member through a further range of prescribed movement past said mute point during which advancing movement of the moving member is not halted by certain contingencies.
Preferably, the method includes continuously checking the distance advanced by the moving member beyond said mute point with a prescribed maximum distance and if interruption of the light beam is not sensed within said prescribed maximum distance, halting the advancing movement of the moving member.
Preferably, the method includes continuously measuring the instantaneous movement of the moving member, separately detecting the position of the mute point when the moving member is physically disposed thereat, checking that the detected mute point coincides with the measured mute point whenever wither mute point condition is sensed, and halting further advancing movement of the moving member immediately upon establishing a difference in the occurrence between the two.